Abstract: Pomegranate peel tannins were extracted by ultrasonic-assisted extraction and purified by Amberlite XAD-16 macroporous resin. Gradient methanol was used as elution solution. Then the components were determined by high performance liquid chromatography (HPLC) analysis. The eluate with the highest content of punicalagin was used for the antimicrobial asssays. Inhibition zone diameters and the minimal inhibitory concentration (MIC) were investigated. The effect of punicalagin on the growth of Staphylococcus aureus was also monitored. HPLC showed that the purity of the eluate increased at first then decreased with the increasing concentration of ethanol. The highest purity among the different eluates was 79.6%. Antimicrobial study demonstrated that punicalagin exhibited good inhibitory effects against Staphylococcus aureus, the MIC was determined as 0.1mg/m L. Punicalagin inhibited the growth of Staphylococcus aureus in a dose-dependent manner.